MOLDRAW prepares a .POV file by clicking the Export keyword of the toolbar and selecting the PovRay[POV]
option.
PovRay files written by MOLDRAW (.POV extension) can be
directly read by the PovRay program. However, the user can also change some of the
features affecting the aspect of the final picture (i.e. atom colors or the
thickness of the bonds). These changes can be easily carried out by editing the
records located at the head of the .POV file.
Setting up the PovRay program
Launch the PovRay program and carry out the operations described
above.
Before any graphical rendering, ensure that the graphic
resolution of PovRay matches that of your screen: check the combo
box (circled in the left picture) to match your own screen resolution. AA
0.3 controls the anti-aliasing feature which ensures topmost quality of
the pictures
Also ensure that the output graphic format of the file
generated by PovRay is PNG (Portable Network Graphic) which is the best
compromise between quality and size.
To do that, open the (Tools--->Edit master
POVRAY.INI) menu of the PovRay program, and edit the INI file. Go to
the bottom of the file and ensure that the record Output_File_Type=n is there. In case it is
missing, simply add it and save the POVRAY.INI file. The record Output_File_name=MyPathName will cause all
the graphic files to be stored under the MyPathName directory. You should now quit and
start again the PovRay program in order the changes to become effective. This
operation is done only once for ever.
Render the molecular structure
As an example lets open the DEFAULT.MOL file (ascorbic acid), then
click the Solid keyword of the toolbar. Click the Export keyword of the toolbar and select the
PovRay [POV] option and save the file with the default name MOLPOV.POV.
Launch the PovRay program, load the MOLPOV.POV file and press the
Run button. The picture will be
saved in a MOLPOV.PNG graphic file within the MyPathName directory if this has been set in the
POVRAY.INI file or in the same directory where the MOLPOV.POV file is stored, in
all other cases. The picture is also rendered on the fly for screen preview. If
all is ok, you should get something similar to the picture below (click on it to
see an enlarged view):
Changing default setting of a POV file
At the top of the MOLPOV.POV file there are records which set
various parameters controlling the final graphic rendering. For instance,
lets change the size of the bonds by doubling their size. To do that, locate the
top of the PovRay file where you should see something like:
Now set the Size_Stick =
.14 and save the POV file and run it again.
Something similar to the following picture should appear on the screen (click on
it to enlarge):
Other effects can be obtained by setting other geometrical
parameters (the size of the atomic spheres can be changed by Radius_X records).
The atom and bond colors are all specified by the Red(R), Green(G) and Blue(B)
convention, in which R=0, G=0, B=0 is black color whereas R=1, G=1, B=1 is white
color. So, for instance, to change the oxygen atom color from red to blue simply
change the record Color_O=rgb<0.,0.,1.>, save it and
run again. The resulting picture should be the one shown below (click on it to
enlarge):
Usually the default PovRay parameters which are stored in the MDRAW.INI file
are such that no cast shadows are computed by PovRay. To set this
option to on (the rendering time will take longer for large structures) set
the record Cast_Shadow=1, save it
and run again.
Some useful PovRay keywords
The PovRay file contains some useful keywords which can be fine
tuned by the user. The most important ones are listed and commented below:
#declare Size_Cell = .01;
Defines the thickness of the unit cell box
#declare Size_Cylinder_Arrows =
.06;
Defines the cylinder diameter of the vibrational frequency
arrows
#declare Size_BaseCone_Arrows =
.15;
Defines the cone diameter of the vibrational frequency
arrows
#declare Scale_Vibra = .9;
Defines the amplitude of each frame composing a vibrational
PovRay movie
#declare Size_Stick =
.054;
Defines the thickness of the bonds
#declare Size_Hbond =
.054;
Defines the thickness of the hydrogen bonds
#declare Cast_Shadow=0;
Set to 1 allows shadows to be cast
#declare Zoom=1;
Defines the level of enlargment of the rendered
picture
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